The urtw driver supports USB 802.11b/g
wireless adapters based on the Realtek RTL8187L and RTL8187B.

These are the modes the urtw driver can
operate in:

BSS mode

Also known as infrastructure mode, this is
used when associating with an access point, through which all traffic
passes. This mode is the default.

monitor mode

In this mode the driver is able to receive packets without associating
with an access point. This disables the internal receive filter and
enables the card to capture packets from networks which it wouldn't
normally have access to, or to scan for access points.

The urtw driver can be configured to use
Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA-PSK and
WPA2-PSK). WPA is the current encryption standard for wireless networks. It is
strongly recommended that WEP not be used as the sole mechanism to secure
wireless communication, due to serious weaknesses in it. The
urtw driver relies on the software 802.11
stack for both encryption and decryption of data frames.